1. Field of the Invention
The present invention relates generally to drilling machinery and more particularly to a portable drilling machine for drilling horizontal boreholes under a street or building or the like to facilitate the installation of underground tubing or cables as may be used to conduct a utility.
2. Background Art
Relatively small diameter horizontal boreholes are often drilled beneath a street or building. Such holes are drilled to accommodate passage of a utility line such as a water, gas or electric line from a main supply trunk running along a street to the basement of a residence or business establishment.
The drilling of a borehole often is accomplished by first laying a frame or track in the basement of a building and then anchoring the frame in position. The frame is laid generally perpendicular to a basement wall so a borehole can be bored through the wall and underground to the utility trunk running along the street. A movable carriage, which carries a drill motor, is mounted to the frame and is movable along the frame or track for advancing a drill bit into the working face of the basement wall. A hydraulic cylinder or the like arranged between the frame and the carriage provides the thrust for moving the carriage relative to the anchored frame to advance the drill motor and bit into the working face.
The drilling apparatus for drilling the boreholes as described should be portable and relatively lightweight. As noted above the apparatus often is used in close quarters such as a basement. Various obstacles such as, for example, a furnace, water heater, piping, laundry tubs and wall panels or room dividers may further restrict the close quarters. Also, access to the work area may be further restricted by a narrow entry, hallway, stairway or the like.
Accordingly, the apparatus preferably should be composed of components that are easily transported and assembled on site. That is the apparatus should be sufficiently portable to be hand carried into the work area by one or two persons. Individual components must be short, narrow and lightweight so the apparatus is easy to set up and, after the job is done, easy to disassemble and carry away.
It also is important to control and maintain the angle of attack of the drill bit relative to the working face. Setting and maintaining the correct attitude throughout the drilling operation insures that the borehole extends in the direction to intersect the trunk line, which may be at some distance from the building and at a different elevation than the drilling site. While existing apparatus provide one or more of the desired features of such drilling apparatus, the portability of the apparatus, simplification of components, ease of assembly and disassembly and direction control are all features that are improved by the present invention.
Accordingly, it is an object of the present invention to provide an improved drilling apparatus of the type used for drilling small diameter boreholes, the apparatus including components that are portable and are easily assembled and disassembled.
Another object of the present invention is to provide drilling apparatus for drilling horizontal boreholes that has improved direction control of the drill bit.
Yet another object is to provide drilling apparatus of the type described that reduces the number of components needed to assemble the apparatus.
A further object of the invention is to provide a drilling apparatus of the type described which eliminates the need to assemble the frame and movable carriage mounted to the frame from separate members.